1. Field of the Invention
The present invention relate to a process for producing a seasoning or food which possesses augmented richness in taste due to the addition of a water-extract of beer yeast and is free from bitterness and odor characteristic of beer yeast.
2. Discussion of the Background
Flavor-imparting functions of monosodium L-glutamic acid (MSG), sodium inosine-5'-monophosphate (IMP) and sodium guanosine-5'-monophosphate (GMP), which are typical flavoring agents, are well known. They have been widely used for the purpose of enhancing such organoleptic properties as flavor and richness in taste, in combination with hydrolysates of vegetable proteins (HVP) or animal proteins (HAP), yeast extracts (YE), amino acids, etc., depending ion their uses.
With the widespread use of such flavoring agents, it has been desired to further enhance or augment their taste-enriching functions, including the function of enhancing thickness, richness and persistence of taste, apart from the enhancement of taste based on the combined use with other flavoring agents capable of imparting saltness, sweetness, sourness, etc.
On the other hand, yeast extracts, i.e., autolysates and hydrolysates of yeast containing various amino acids and minerals, have been applied to various foods and seasonings. Yeast extracts have hitherto been produced by autolysis involving the decomposition of cells of yeast or by hydrolysis conducted under severe conditions involving treatments at elevated temperatures with the addition of chemicals for hydrolysing the yeast cells.
The inventors have previously found that water-extracts of yeast, namely extracts from yeast obtained by extraction with hot water under mild conditions where no substantial decomposition of yeast cells takes place, have unique taste-enriching effects different from those of any known combinations of flavoring agents (see Japanese Patent Application Nos. 280,981/84 and 280,982/84) and continued investigations on optimum extraction conditions, storage stability of extracts, etc. As a consequence, it has been found that extracts obtained from beer yeast by means of hot water extraction involving no substantial decomposition of yeast cells tend to assume an odor and bitterness characteristic of beer yeast and that their taste-enriching function tends to be impaired during the course of sterilization after extraction.
As far as hydrolysates and autolysates of yeast are concerned, it has been known that washing with water and supercritical gas extraction can be effective for the removal of the bitterness. It has also been proposed to subject hydrolysates and autolysates of yeast to various treatments to remove odor, such as washing with organic solvents, or to mask their odor by various means. However, nothing has been known regarding the bitterness and odor of the hot water extracts from yeast, as well as on the protection, during thermal sterilization, of the taste-enriching function of hot water extracts from yeast.